Electrical apparatus comprising perfluoroazaolefin as liquid dielectric

ABSTRACT

Perfluoroazaolefins are useful as liquid dielectrics in electrical apparatus.

United 5 States Patent [191 Oxenrider et al.

ELECTRICAL APPARATUS COMPRISING PERFLUOROAZAOLEFIN AS LIQUID DIELECTRIC- Inventors: Bryce c. oxenrider, Florham, NLL;

Cyril Woolf, Morristown, N.J.; Wilhelmus M. Beyleveld, Deventer,

Appl. No.1 161,934

US. Cl 317/258, 252/63.7, 260/566 R,

260/566 D, 260/583 GG Int. Cl. IIOIgI/OO, I-lOlg 3/04 Field of Search .J. 252/63.7; 260/566' D,

[4 1 July 17, 1973 [56] References Cited UNITED STATES PATENTS 2,966,517 12/1960 Hauptschein 260/583 06 3,309,606 3/1967 Forster et al. 3 l7/258 X 3,259,817 7/1966 Adany.... 317/258 2,751,414 6/1956 Miller 260/566 D 3,038,000 6/1962 Schmidt 252/63.7 X 2,643,267 6/1953 Pearlson et al. 260/566 D 3,660,511 5/1972 Ogden 260/566 R FOREIGN PATENTS OR APPLICATIONS 666,733 2/ 1952 Great Britain 260/583 GG ABSTRACT Perfluoroazaolefins are useful as liquid dielectrics in electrical apparatus.

'5 Claims, No Drawings ELECTRICAL APPARATUS COMPRISING PERFLUOROAZAOLEFIN AS LIQUID DIELECTRIC Electrical apparatus comprising a sealed casing, spaced electrical elements therein adapted to be subjected to differences of electrical potential, and a liquid dielectric between said elements are well known. This invention provides the improvement wherein the liquid dielectric comprises a perfluoroazaolefin having the formula wherein each R, is independently a perfluoroalkyl radical of one to three carbon atoms and A is fluorine or a radical having the formula wherein each R, is independently a perfluoroalkyl radical of one to three carbon atoms. Preferably, each R, is trifluoromethyl. The liquid dielectric can consist of one or more such perfluoroazaolefin s, alone or together with other suitable dielectric liquids. The perfluoroazaolefins are employed in accordance with conventional methods for'employing liquid dielectrics.

2,, in the presence of an ionizable fluoride salt in an aprotic, polar liquid reaction medium, as represented by the following equation wherein R, is as defined herein. The reaction is carried out under substantially anhydrous conditions at a temperature ranging from about 50 to about 150 C. Acetonitrile is preferred as the liquid reaction medium and The perfluoroazaolefins employed in this invention 4 wherein A is fluorine are known compounds, being disclosed, for example, in U.S. Pat. No. 2,643,267 andCanadian Pat. No. 703,479.

The perfluoroazaolefins employed in this invention wherein A has the formula are novel compounds claimed in our copending application Ser. No. 161,349, filed concurrently herewith. The pertinent subject matter of the copending application is incorporated herein byreference. As disclosed in the copending application, perfluoroazaolefins having the formula are prepared by reacting a perfluoroalkylidene imine having the formula with a perfluoroazaolefin having the formula potassium fluoride is preferred as the fluoride salt. Since the fluoride salt also acts as an acceptor of the hydrogen fluoride which is generated as a by-product, at least one mole of the fluoride salt. is employed for each mole of hydrogen fluoride generated. The perfluoroazaolefin product is recovered from the reaction mixture by fractional distillation.

The dielectric properties of two representative per-- fluoroazaolefins of this invention are shown below in Table I.

TABLE I Property Compound A Compound 8' Boiling Point 50C. C. Freezing Point -l00C. 4 2C. Specific Gravity 1.6 Y 1.7 Dielectric Constant, l ltc (ASTM D-l50) 1.8 2.2 Dielectric Stren th, kv./mil (ASTM -877) 27.8 28.3 Dissipation Factor, 1 kc (ASTM D450) 0.0005 0.0006 Volume Reliltivit ohm-cm (ASTM D457) Not Measured 3.96 X 10" 'Perfluoro-Z,4-dimethyl-3-aza-2-pentene 'Perfluoro-2,4,4,6-tetrsmethyl-3,5-diaza-2,S-heptadiene obtained. The liquid was identified as perfluoro- 2,4,4,6-tetramethyl-3,5-diaza-2,5-heptadiene.

We claim:

1. In an electrical apparatus comprising a sealed casing, spaced electrical elements therein adapted to be subjected to differences of electrical potential, and a liquid dielectric between said elements, the improvement wherein the liquid dielectric comprises a perfluoroazaolefin having the formula 3 i 4 wherein each R is a perfluoroalkyl radical of l to 3 car- 4. The improvement of claim 1 wherein A has the hon atoms and A is fluorine or a radical having the forform l mula Rf R v he each Rfis a fl lk l radical of 1 to 3 cap 1 wherein each R, is a perfluoroalkyl radical of l to 3 carbon atoms. bon atoms.

2. The improvement of claim 1 wherein A is fluorine The improvement of claim 4 wherein each r 3. The improvement of claim 2 wherein each R,is trifluoromethyl. fluoromethyl. 

2. The improvement of claim 1 wherein A is fluorine
 3. The improvement of claim 2 wherein each Rf is trifluoromethyl.
 4. The improvement of claim 1 wherein A has the formula
 5. The improvement of claim 4 wherein each Rf is trifluoromethyl. 